Peptides having amino acid sequences comparable to those found in peptidoglycans (PG) and PG-precursors will be synthesized and used either as enzyme substrates or as immunogens. For the soluble exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61, substrates, inhibitors and affinity labelling reagents will be designed to study the active site of the enzyme, and particularly whether penicillin binds as a D-Ala-D-Ala analogue. To study the assembly of PG in the cell wall, the complex mixture of transpeptidase(s), carboxypeptidase(s) and amidase(s) of Micrococcus luteus will be studied with specially designed substrates to differentiate their specificities. Membrane-bound enzymes will be studied in toluene shocked cells, using either a soluble peptidoglycan (SPG) isolated from this organism as a possible intermediate in peptidoglycan biosynthesis or smaller synthetic substrates. The effects of penicillin on the individual reactions will be studied. The objective is to identify the sequence of reactions, the points of regulation and the target(s) of penicillin. In addition, synthetic PG-like polypeptides and SPG will be used as immunogens in strains of inbred mice to test the immunogenetic control over the response to PG and to their peptide sequences.